Wireless system with transmitter having multiple transmit antennas and combining open loop and closed loop transmit diversities

ABSTRACT

A wireless communication system ( 40 ). The system comprises transmitter circuitry ( 42 ) comprising encoder circuitry ( 44 ) for receiving a plurality of symbols (S i ). The system further comprises a plurality of antennas (AT 1 -AT 4 ) coupled to the transmitter circuitry and for transmitting signals from the transmitter circuitry to a receiver (UST), wherein the signals are responsive to the plurality of symbols. Further, the encoder circuitry is for applying open loop diversity and closed loop diversity to the plurality of symbols to form the signals.

CROSS-REFERENCES TO RELATED APPLICATIONS

More than one reissue application has been filed for the reissue of U.S.Pat. No. 6,594,473. The reissue applications are application Ser. No.11/287,564 and the instant reissue application.

This application claims the benefit, under 35 U.S.C. §119(e)(1), of U.S.Provisional Application No. 60/136,413, filed May 28, 1999, andincorporated herein by this reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

The present embodiments relate to wireless communications systems and,more particularly, to transmitters with multiple transmit antennas usedin such systems.

Wireless communications have become very prevalent in business,personal, and other applications, and as a result the technology forsuch communications continues to advance in various areas. One suchadvancement includes the use of spread spectrum communications,including that of code division multiple access (“CDMA”) and widebandcode division multiple access (“WCDMA”) cellular communications. In suchcommunications, a user station (e.g., a hand held cellular phone)communicates with a base station, where typically the base stationcorresponds to a “cell.”

Due to various factors including the fact that CDMA communications arealong a wireless medium, an originally transmitted communication from abase station to a user station may arrive at the user station atmultiple and different times. Each different arriving signal that isbased on the same original communication is said to have a diversitywith respect to other arriving signals originating from the sametransmitted communication. Further, various diversity types may occur inCDMA communications, and the CDMA art strives to ultimately receive andprocess the originally transmitted data by exploiting the effects oneach signal that are caused by the one or more diversities affecting thesignal.

One type of CDMA diversity occurs because a transmitted signal from thebase station is reflected by objects such as the ground, mountains,buildings, and other things that it contacts. As a result, a same singletransmitted communication may arrive at the receiver at numerousdifferent times, and assuming that each such arrival is sufficientlyseparated in time, then each different arriving signal is said to travelalong a different channel and arrive as a different “path.” Thesemultiple signals are referred to in the art as multiple paths ormultipaths. Several multipaths may eventually arrive at the user stationand the channel traveled by each may cause each path to have a differentphase, amplitude, and signal-to-noise ratio (“SNR”). Accordingly, forone communication between one base station and one user station, eachmultipath is a replica of the same user information, and each path issaid to have time diversity relative to other mulitpath(s) due to thedifference in arrival time which causes different (uncorrelated)fading/noise characteristics for each multipath. Although multipathscarry the same user information to the receiver, they may be separatelyrecognized by the receiver based on the timing of arrival of eachmultipath. More particularly, CDMA communications are modulated using aspreading code which consists of a series of binary pulses, and thiscode runs at a higher rate than the symbol data rate and determines theactual transmission bandwidth. In the current industry, each piece ofCDMA signal transmitted according to this code is said to be a “chip,”where each chip corresponds to an element in the CDMA code. Thus, thechip frequency defines the rate of the CDMA code. Given the use oftransmission of the CDMA signal using chips, then multipaths separatedin time by more than one of these chips are distinguishable at thereceiver because of the low autocorrelations of CDMA codes as known inthe art.

In contrast to multipath diversity which is a natural phenomenon, othertypes of diversity are sometimes designed into CDMA systems in an effortto improve SNR, thereby improving other data accuracy measures (e.g.,bit error rate (“BER”), frame error rate (“FER”), and symbol error rate(“SER”)). An example of such a designed diversity scheme is antennadiversity and is introduced here since it has particular application tothe preferred embodiments discussed later. Antenna diversity, orsometimes referred to as antenna array diversity, describes a wirelesssystem using more than one antenna by a same station. Antenna diversityoften proves useful because fading is independent across differentantennas. Further, the notion of a station using multiple antennas ismore typically associated with a base station using multiple antennas toreceive signals transmitted from a single-antenna mobile station,although more recently systems have been proposed for a base stationusing multiple antennas to transmit signals transmitted to asingle-antenna mobile station. Each of these alternatives is furtherexplored below.

Certain antenna array diversity techniques suggest the use of more thanone antenna at the receiver, and this approach is termed receive antennadiversity. For example, in prior art analog systems, often a basestation receiver was equipped with two antennas, each for receiving asignal from a single-antenna mobile station. Thus, when thesingle-antenna mobile station transmits to the base station, eachreceiver antenna provides at least one corresponding received signal forprocessing. By implementing multiple receive antennas, the performanceof an ideal receiver is enhanced because each corresponding receivedsignal may be separately processed and combined for greater dataaccuracy.

More recently there have been proposals to use more than one antenna atthe transmitter, and this approach is termed transmit antenna diversity.For example, in the field of mobile communications, a base stationtransmitter is equipped with two antennas for transmitting to asingle-antenna mobile station. The use of multiple antennas at the basestation for transmitting has been viewed as favorable over usingmultiple antennas at the mobile station because typically the mobilestation is in the form of a hand-held or comparable device, and it isdesirable for such a device to have lower power and processingrequirements as compared to those at the base station. Thus, the reducedresources of the mobile station are less supportive of multipleantennas, whereas the relatively high-powered base station more readilylends itself to antenna diversity. In any event, transmit antennadiversity also provides a form of diversity from which SNR may beimproved over single antenna communications by separately processing andcombining the diverse signals for greater data accuracy at the receiver.Also in connection with transmit antenna diversity and to furthercontrast it with multipath diversity described above, note that themultiple transmit antennas at a single station are typically withinseveral meters (e.g., three to four meters) of one another, and thisspatial relationship is also sometimes referred to as providing spatialdiversity. Given the spatial diversity distance, the same signaltransmitted by each antenna will arrive at a destination (assuming noother diversity) at respective times that relate to the distance betweenthe transmitting antennas. However, the difference between these timesis considerably smaller than the width of a chip and, thus, the arrivingsignals are not separately distinguishable in the same manner as aremultipaths described above.

Given the development of transmit antenna diversity schemes, two typesof signal communication techniques have evolved to improve datarecognition at the receiver given the transmit antenna diversity,namely, closed loop transmit diversity and open loop transmit diversity.Both closed loop transmit diversity and open loop transmit diversityhave been implemented in various forms, but in all events the differencebetween the two schemes may be stated with respect to feedback.Specifically, a closed loop transmit diversity system includes afeedback communication channel while an open loop transmit diversitysystem does not. Both of these systems as well as the distinctionbetween them are further detailed below.

FIG. 1 illustrates a prior art closed loop transmit antenna diversitysystem 10 including a transmitter 12 and a receiver 14. By way ofexample, assume that transmitter 12 is a base station while receiver 14is a mobile station. Also, for the sake of simplifying the discussion,each of these components is discussed separately below. Lastly, notethat the closed loop technique implemented by system 10 is sometimesreferred to in the art as a transmit adaptive array (“TxAA”), whileother closed loop techniques also should be ascertainable by one skilledin the art.

Transmitter 12 receives information bits B_(i) at an input to a channelencoder 13. Channel encoder 13 encodes the information bits B_(i) in aneffort to improve raw bit error rate. Various encoding techniques may beused by channel encoder 13 and as applied to bits B_(i), with examplesincluding the use of convolutional code, block code, turbo code, or acombination of any of these codes. The encoded output of channel encoder13 is coupled to the input of an interleaver 15. Interleaver 15 operateswith respect to a block of encoded bits and shuffles the ordering ofthose bits so that the combination of this operation with the encodingby channel encoder 13 exploits the time diversity of the information.For example, one shuffling technique that may be performed byinterleaver 15 is to receive bits in a matrix fashion such that bits arereceived into a matrix in a row-by-row fashion, and then those bits areoutput from the matrix to a symbol mapper 16 in a column-by-columnfashion. Symbol mapper 16 then converts its input bits to symbols,designated generally as S_(i). The converted symbols S_(i) may takevarious forms, such as quadrature phase shift keying (“QPSK”) symbols,binary phase shift keying (“BPSK”) symbols, or quadrature amplitudemodulation (“QAM”) sybmols. In any event, symbols S_(i) may representvarious information such as user data symbols, as well as pilot symbolsand control symbols such as transmit power control (“PC”) symbols andrate information (“RI”) symbols. Symbols S_(i) are coupled to amodulator 18. Modulator 18 modulates each data symbol by combining itwith, or multiplying it times, a CDMA spreading sequence which can be apseudonoise (“PN”) digital signal or PN code or other spreading codes(i.e., it utilizes spread spectrum technology). In any event, thespreading sequence facilitates simultaneous transmission of informationover a common channel by assigning each of the transmitted signals aunique code during transmision. Further, this unique code makes thesimultaneously transmitted signals over the same bandwidth disinguishbleat receiver 14 (or other receivers). Modulator 18 has two outputs, afirst output 18 ₁ connected to a multiplier 20 ₁ and a second output 18₂ connected to a multiplier 20 ₂. Each of multipliers 20 ₁ and 20 ₂multiplies its input times a weight value, W₁ and W₂, respectively, andprovides an output to a respective transmit antenna A12 ₁ and A12 ₂. Byway of example, assume that transmit antennas A12 _(1 and A12) ₂ areapproximately three to four meters apart from one another.

Receiver 14 includes a receive antenna A14 ₁ for receivingcommunications from both of transmit antennas A12 ₁ and A12 ₂. Recallthat such communications may pass by various multipaths, and due to thespatial relationship of transmit antennas A12 ₁ and A12 ₂, eachmultipath may include a communication from both transmit antenna A12 ₁and transmit antenna A12 ₂. In the illustration of FIG. 1, a total of jmultipaths are shown. Further, each multipath will have a fading channelparameter associated with it, that is, some value that reflects thechannel effects on the signal carried by the channel. By way ofreference, the character α is used in this document to identify thisfading parameter; moreover, in FIG. 1, the convention α_(i) ^(j) isused, where i=1 identifies a path transmitted by the antenna A12 ₁, i=2identifies a path transmitted by the antenna A12 ₂, and j identifies themultipath. Within receiver 14, signals received by antenna A14 ₁ areconnected to a despreader 22. Despreader 22 operates according to knownprinciples, such as by multiplying the CDMA signal times the CDMA codefor receiver 14, thereby producing a despread symbol stream at itsoutput and at the symbol rate. The despread signals output by despreader22 are coupled to an open loop diversity decoder 23, and also to achannel estimator 24. Channel estimator 24 determines estimated channelimpulse responses based on the incoming despread data. Further, channelestimator 24 provides two outputs. A first output 24 ₁ from channelestimator 24 outputs the estimated channel impulse responses to openloop diversity decoder 23. In response to receiving the estimates, openloop diversity decoder 23 applies the estimates to the despread datareceived from despreader 22; further in this regard and although notseparately shown, the application of the estimate to the data may be byway of various methods, such as maximal ratio combining (MRC) and usinga rake receiver. A second output 242 from channel estimator 24communicates the estimates, or values derived from those estimates, backto transmitter 12 via a feedback channel. These feedback values are theweights W₁ and W₂ described above with respect to multipliers 20 ₁ and20 ₂ of transmitter 12.

Returning to open loop diversity decoder 23 of receiver 14, once itapplies the estimates to the despread data, its result is output to adeinterleaver 25 which operates to perform an inverse of the function ofinterleaver 15, and the output of deinterleaver 25 is connected to achannel decoder 26. Channel decoder 26 may include a Viterbi decoder, aturbo decoder, a block decoder (e.g., Reed-Solomon decoding), or stillother appropriate decoding schemes as known in the art. In any event,channel decoder 26 further decodes the data received at its input,typically operating with respect to certain error correcting codes, andit outputs a resulting stream of decoded symbols. Indeed, note that theprobability of error for data input to channel decoder 26 is far greaterthan that after processing and output by channel decoder 26. Forexample, under current standards, the probability of error in the outputof channel decoder 26 may be between 10⁻³ and 10 ⁻⁶. Finally, thedecoded symbol stream output by channel decoder 26 may be received andprocessed by additional circuitry in receiver 14, although suchcircuitry is not shown in FIG. 1 so as to simplify the presentillustration and discussion.

Having detailed system 10, attention is now returned to itsidentification as a closed loop system. Specifically, system 10 is nameda closed loop system because, in addition to the data communicationchannels from transmitter 12 to receiver 14, system 10 includes thefeedback communication channel for communicating weights W₁ and W₂ fromreceiver 14 to transmitter 12; thus, the data communication and feedbackcommunication channels create a circular and, hence, “closed” loopsystem. Note further that weights W₁ and W₂ may reflect various channelaffecting aspects. For example, receiver 14 may ascertain a level offading in signals it receives from transmitter 12, such as may be causedby local interference and other causes such as the Doppler rate ofreceiver 14 (as a mobile station), and in any event where the fading maybe characterized by Rayleigh fading. As a result, receiver 14 feeds backweights W₁ and W₂ and these weights are used by multipliers 20 ₁ and 20₂, thereby applying weight W₁ to various symbols to provide atransmitted signal along transmitter antenna A12 ₁ and applying weightW₂ to various symbols to provide a transmitted signal along transmitterantenna A12 ₂. Thus, for a first symbol S₁ to be transmitted by station12, it is transmitted as part of a product W₁S₁ along transmitterantenna A12 ₁ and also as part of a product W₂S₂ along transmitterantenna A12 ₂. By way of illustration, therefore, these weightedproducts are also shown in FIG. 1 along their respective antennas.

Turning now to a prior art open loop transmit diversity system, it maydescribed generally and in comparison to the closed loop system 10 ofFIG. 1, where the primary distinction is that the prior art open looptransmit diversity system does not require feedback. Thus, to depict anopen loop system the illustration of FIG. 1 may be modified by removingthe feedback channel, weights W₁ and W₂ and multipliers 20 ₁ and 20 ₂,with the remaining blocks thereby generally illustrating an open looptransmit diversity system. Given that the open loop transmit diversitysystem does not include feedback, it instead employs an alternativetechnique to adjust data differently for each of its transmit antennas.Therefore, the open loop system receiver then attempts to properlyevaluate the data in view of the known transmitter adjustment. Thus, theprocessing and algorithms implemented within the receiver decoder of anopen loop system will differ from those in a closed loop system.

To further depict open loop transmit diversity, FIG. 2 illustrates, byway of example, a prior art open loop transmitter 30 that is referred toas providing space time block coded transmit antenna diversity (“STTD”),and further in this regard transmitter 30 includes an STTD encoder 32.STTD encoder 32 has an input 34, which by way of example is shown toreceive a first symbol S₁ at a time T followed by a second symbol S₂ ata time 2T. For the sake of the present example, assume that symbols S₁and S₂ are QPSK symbols. STTD encoder 32 has two outputs 36 ₁ and 36 ₂,each connected to a respective antenna A32 ₁ and A32 ₂.

The operation of transmitter 30 is now explored, and recall in generalfrom above that open loop system transmitters adjust data differently ateach transmit antenna without the assistance of feedback. In the case oftransmitter 30, STTD encoder 32 first buffers a number of symbols equalto the number of transmit antennas. In the example of FIG. 2 which hastwo transmit antennas A32 ₁ and A32 ₂, STTD encoder 32 therefore bufferstwo symbols (e.g., S₁ and S₂). Next, STTD encoder 32 directly transmitsthe buffered symbols along antenna A32 ₁ and, thus, in FIG. 2 symbol S₁is transmitted at a time T′ and symbol S₂ is transmitted at a time 2T′.During the same time, however, and for transmission along antenna A32 ₂,the complex conjugates of the symbols are formed and reversed in order.For the example of FIG. 2, therefore, these two operations create, inthe reversed order, a sequence of S*₂ and S*₁. Moreover, whentransmitted along antenna A32 ₂, the negative value of the first ofthese two symbols is transmitted while the positive value of the secondsymbol is transmitted. Accordingly, in FIG. 2 and with respect toantenna A32 ₂, a symbol −S*₂ is transmitted at a time T′ and a symbolS*₁ is transmitted at a time 2T′. From the symbols transmitted by STTDencoder 32, a compatible receiver is therefore able to resolve thesymbols in a manner that often yields favorable data error rates evengiven relatively large Doppler rates. Finally, note also by way of analternative example that if symbols S₁ and S₂ were BPSK symbols, thensuch symbols would include only real components (i.e., they do notinclude a complex component). In this case, along antenna A32 ₁ system30 would transmit symbol S₁ at time T′ and symbol S₂ at time 2T′, whilealong antenna A32 ₂ system 30 would transmit symbol S₂ at time T′ andsymbol −S₁ at time 2T′.

Having detailed both closed loop and open loop transmit antennadiversity systems, additional observations are now made regarding thebenefits and drawbacks of each. In general, under the ideal situation, aclosed loop system outperforms an open loop system for a giventransmitted signal power. However, due to non-ideal occurrences in thefeedback information, a closed loop system may be inferior to an openloop system in some situations. For example, as Doppler fadingincreases, by the time the feedback information is received by thetransmitter, the weights included or derived from the feedbackinformation may be relatively outdated and therefore less effective whenapplied to future transmissions by the transmitter. Conversely, becausethe open loop system does not implement feedback from the receiver tothe transmitter, then such a system may provide greater performance in ahigh Doppler environment. In the prior art, the drawbacks of both theclosed loop and open loop systems have been addressed in one manner byfurther increasing the number of antennas in either the closed loop oropen loop system. While this approach may improve error rates ascompared to fewer antennas for the same system, there are diminishingreturns in data error rates to be considered versus the complexities ofadding more antennas to a system. Moreover, for each antenna added to aclosed loop diversity system, there is a corresponding increase in theamount of bandwidth required to accommodate the additional feedbackinformation required for the added transmit antenna.

In view of the above, there arises a need to improve upon the drawbacksof prior art closed loop systems and prior art open loop Systems, andsuch a need is addressed by the preferred embodiments described below.

BRIEF SUMMARY OF THE INVENTION

In the preferred embodiment, there is a wireless communication system.The system comprises transmitter circuitry comprising encoder circuitryfor receiving a plurality of symbols. The system further comprises aplurality of antennas coupled to the transmitter circuitry and fortransmitting signals from the transmitter circuitry to a receiver,wherein the signals are responsive to the plurality of symbols. Further,the encoder circuitry is for applying open loop diversity and closedloop diversity to the plurality of symbols to form the signals. Othercircuits, systems, and methods are also disclosed and claimed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 illustrates an electrical diagram of a prior art closed looptransmit antenna diversity system.

FIG. 2 illustrates an electrical diagram of a transmitter in a prior artopen loop transmit antenna diversity system.

FIG. 3 illustrates a diagram of a cellular communications system by wayof a contemporary example in which the preferred embodiments operate.

FIG. 4 illustrates an electrical diagram of the preferred base stationtransmitter and mobile station receiver of FIG. 3.

FIG. 5 illustrates an open and closed loop encoder for transmittingalong two antennas.

FIG. 6 illustrates an OTD encoder for transmitting open loop diversesignals along four antennas.

FIG. 7 illustrates a space time block coded transmit antenna diversityencoder for transmitting open loop diverse signals along four antennas.

FIG. 8 illustrates a time switched time diversity encoder fortransmitting open loop diverse signals along four antennas.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2 were described above in the Background Of The Inventionsection of this document and the reader is assumed to be familiar withthe details described in that section.

FIG. 3 illustrates a diagram of a cellular cunitions system 40 by way ofa contemporary example in which the preferred embodiments operate.Within system 40 is shown a base station BST, which includes fourantennas AT1 through AT4 along which base station BST may transmit (orreceive) CDMA or WCDMA signals. In the preferred embodiment, eachantenna in the group of antennas AT1 through AT4 is within approximatelythree to four meters of another antenna in the group. In otherembodiments, however, note that the multiple transmit antennas may bemuch closer to one another; for example, in an environment where basestation BST and user station UST are both indoor stations, the distancebetween the multiple transmit antennas of base station BST may be on theorder of inches. Returning to the example of FIG. 1, the general area ofintended reach of base station BST defines a corresponding CELL and,thus, base station BST is intended to generally communicate with othercellular devices within that CELL. Beyond the CELL there may be othercells, each having its own corresponding base station, and indeed theremay be some overlap between the illustrated CELL and one ore more othercells adjacent the illustrated CELL. Such overlap is likely to supportcontinuous communications should a mobile communication station movefrom one cell to another. Further in this regard, system 40 alsoincludes a user station UST, which is shown in connection with a vehicleV to demonstrate that user station UST is mobile. By way of example,user station UST includes a single antenna ATU for both transmitting andreceiving cellular communications.

In various respects, system 40 may operate according to known generaltechniques for various types of cellular or other spread spectrumcommunications, including CDMA or WCDMA communications. Such generaltechniques are known in the art and include the commencement of a callfrom user station UST and the handling of that call by base station BST.Where system 40 differs from the prior art, however, is the system for,and method of, communicating signals from each of the four antennas AT1through AT4 to user station UST. These distinctions are further detailedbelow in connection with FIG. 4.

FIG. 4 illustrates an electrical block diagram of base station BST anduser station UST from system 40 of FIG. 3. For the sake of discussion,each of base station BST and user station UST is separately detailedbelow. By way of introduction, however, one skilled in the art willappreciate from the following details that system 40 presents atransmitter with more than two antennas (e.g., four in FIG. 4), whereits signals are communicated using a combination of open loop and closedloop communication techniques.

Looking to base station BST in FIG. 4, it includes a transmitter 42which further includes two separate STTD encoders 44 and 46, both ofwhich receive the same stream of symbols. By way of example, two inputsymbols are shown, a symbol S₁ at a time T and a symbol S₂ and a time2T. Symbols S₁ and S₂ may be provided by other circuitry (not shown)within base station BST that is either part of transmitter 42 orexternal from it, and such other circuitry may be appreciated by way ofexample with reference to the circuitry preceding modulator 18 inFIG. 1. Returning to STUD encoder 44, it has outputs 44 ₁ and 44 ₂connected to respective antennas AT1 and AT2. STTD encoder 46 hasoutputs 46, and 46 ₂ connected to respective antennas AT3 and AT4.

The operation of transmitter 42 is as follows. First, recall it is notedabove that system 40 combines open loop and closed loop communicationtechniques. In the embodiment of FIG. 4 and as now presented in detail,this combination is achieved by implementing an open loop communicationtechnique per STTD encoder and by implementing a closed loopcommunication technique as between one STTD encoder versus another STUDencoder. As another manner of stating the combination and as furtherappreciated below, system 40 implements an open loop communicationtechnique for a first and second pair of its transmit antennas, and itfurther implements a closed loop diversity communication technique asbetween the first transmit antenna pair relative to the second transmitantenna pair. Each of these different techniques, and their combination,is discussed below.

The open loop communication aspect of transmitter 42 may be appreciatedby way of example with respect to STUD encoder 44, and note that thesignals output by STTD encoder 44 to antennas AT1 and AT2 are shown inFIG. 4; from these signals, it may be appreciated that all of thesignals have a common factor of a weight, W₁, which is furtherappreciated from the later discussion of the closed loop technique andwhich for the immediately following discussion is ignored so as toappreciate the open loop technique. Looking now to the factors otherthan the weight, W₁, in the output signals of STUD encoder 44, oneskilled in the art will appreciate that such signals alone represent anopen loop diversity communication technique. Specifically, STTD encoder44 first buffers a number of symbols equal to the number of transmitantennas to which it is connected, which is two antennas (i.e., AT1 andAT2) in the present example. Thus, STTD encoder 44 buffers symbols S₁and S₂. Next, STUD encoder 44 directly transmits the buffered symbols S₁and S₂ along antenna AT1 and, thus, in FIG. 4 symbol S₁ is transmittedat a time T′ and symbol S₂ is transmitted at a time 2T′. During the sametime, and for transmission along antenna AT2, the complex conjugate ofthe symbols are formed and reversed in order, and after the reversal thenegative value of the first symbol conjugate is communicated (i.e.,−S*₂) at time T′ followed by the positive value of the second symbolconjugate (i.e., S*₁) at time 2T′. Given the preceding with respect tothe pair of antennas AT1 and AT2, it should be appreciated that system40 implements an open loop communication technique relative to thattransmit antenna pair.

The open loop diversity communication technique of system 40 may beappreciated further with reference to the pair of transmit antennas AT3and AT4 and STTD encoder 46 which outputs signals to those antennas.Looking to the signals output along antennas AT3 and AT4, they each havea common factor of a weight, W₂. Looking to the factors other than theweight, W₂, in the output signals of STTD encoder 46, such signals alonealso represent an open loop diversity communication technique.Specifically, STTD encoder 46 also buffers symbols S₁ and S₂ andtransmits them in the same manner as STTD encoder 44 described above.Thus, STTD encoder 46 directly transmits symbols S₁ and S₂ along antennaAT3 (at time T′ and 2T, respectively) and STTD 46 encoder at the sametime transmits −S*₂, the negative symbol conjugate of the second symbol,at time T′ followed by S*₁, the positive symbol conjugate of the firstsymbol, at time 2T′. These communications further demonstrate thatsystem 40 implements an open loop communication technique relative tothe pair of transmit antennas AT3 and AT4.

The closed loop diversity communication aspect of transmitter 42 may beappreciated by examining the differences in the output signals of STTDencoders 44 and 46, and further in view of user station UST. Lookingfirst to user station UST, it includes a despreader 48, an open andclosed loop diversity decoder 49, a channel estimator 50, adeinterleaver 51, and a channel decoder 52. Each of these devices may beconstructed and operate according to techniques in various respectsascertainable by one skilled in the art and in view of the earlierdiscussion relative to FIG. 1; further, however, recall that system 40communicates signals using a combination of open loop and closed loopcommunication techniques. Thus, decoder 49 should be constructed toperform both open loop and closed loop diversity decoding, andpreferably these operations should be simultaneous with respect to bothdiversity types since those diversity types are both combined into thesignals received by receiver UST, as will be appreciated further in viewof the combined open and closed loop transmit antenna diversitytechniques described in this document. At the present point in thisdiscussion, note that channel estimator 50 determines estimated channelimpulse responses based on the incoming despread data as furtherdetailed below, and in addition to providing the estimates to decoder 49via an output 50 ₁, it also provides via an output 50 ₂ the estimates,or values derived from those estimates, back to base station BST via afeedback channel. These feedback values are shown in FIG. 4 as weightsW₁ and W₂ and may be returned individually or as a ratio (e.g., W₂/W₁).Returning now to transmitter 42 of base station BST, its use of weightsW₁ and W₂ to implement its closed loop aspect now may be appreciated.Specifically, weight W₁ is coupled to a mutliplier 44 _(M) associatedwith or as part of STTD encoder 44, and as a result weight W₁ ismultiplied times each symbol to be output by STTD encoder 44.Accordingly, the factor of W₁ may be seen in FIG. 4 in each of theoutput signals from STTD encoder 44 (i.e., as transmitted by antennasAT1 and AT2). Similarly, weight W₂ is coupled to a mutliplier 46 _(M)associated with or as part of STTD encoder 46, and as a result weight W₂is multiplied times each symbol to be output by STTD encoder 46.Accordingly, the factor of W₂ may be seen in FIG. 4 in each of theoutput signals from STTD encoder 46 (i.e., as transmitted by antennasAT3 and AT4). Thus, different weights are included within differentoutput signals of base station BST and those weights are in response tothe feedback channel from user station UST. Accordingly, the use of thedifferent weights by system 40 demonstrates a closed loop communicationtechnique as between one pair of transmit antennas (e.g., AT1 and AT2)relative to another pair of transmit antennas (e.g., AT3 and AT4).

Having demonstrated the use of weights W₁ and W₂ in the closed loopaspect of system 40, attention is now directed to the generation of theoptimum value for those weights by channel estimator 50. Specifically,these weights are calculated as follows. First, the following Equation 1defines a matrix, W, for further generation of the weights W₁ and W₂:

$\begin{matrix}{\overset{\_}{W} = \begin{bmatrix}W_{1} \\W_{2}\end{bmatrix}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Next, the following Equations 2 and 3 define channel impulse responsematrices for each of antennas AT1 through AT4 in system 40, where h_(i)is the channel impulse response matrix for antenna AT1 in system 40.H₁=[h₁h₃]  Equation 2H₂=[h₂h₄]  Equation 3

For each of Equations 2 and 3, if there are a total of N resolvablemultipaths from base station BST to user station UST, then h_(i) isfurther defined as a vector relating to each of those multipaths asshown in the following Equation 4:

$\begin{matrix}{h_{i} = \begin{bmatrix}\alpha_{i}^{1} \\\alpha_{i}^{2} \\\; \\\alpha_{i}^{N}\end{bmatrix}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

Next, a term r₁ is defined in Equation 5 and is the signal received byuser station UST after despreading the signal transmitted over time [0,T) and taking into account a noisefactor, n₁:r₁=h₁W₁S₁−h₂W₁S*₂+h₃W₂S₁−h₄W₂S*₂+n₁   Equation 5

Similarly, a term r₂ is defined in Equation 6 and is the signal receivedby user station UST after despreading the signal transmitted over time[T, 2T), and taking into account a noise factor, n₂:r₂=h₁W₁S₂+h₂W₁S*₁+h₃W₂S₂+h₄W₂S*₁+n₂   Equation 6

Rearranging the preceding yields Equation 7 for the value r₁:r₁=(h₁W₁+h₃W₂)S₁−(h₂W₁+h₄W₂)S*₂+n₁=H₁ WS₁−H₂WS₂+n₁   Equation 7

Rearranging the preceding yields Equation 8 for the value r₂:r₂=(h₂W₁+h₄W₂)S*₁+(h₁W₁+h₃W₂)S₂+n₂=H₂ WS*₁+H₁WS*₂+n₂   Equation 8

When signals r₁ and r₂ reach decoder 52, they are decoded as known inthe STFD art. This decoding therefore may be represented as in thefollowing Equation 9, and using the conventions that the symbol (.)^(H)denotes conjugate transpose of a vector, the symbol (.)^(T) denotes atranspose of a vector, and the symbol (.)* denotes its conjugate:

$\begin{matrix}{{{{\overset{\_}{W}}^{H}H_{1}^{H}r_{1}} + {{\overset{\_}{W}}^{T}H_{2}^{T}r_{2}^{*}}} = {{\left( {{\overset{\_}{W}}^{H}H_{1}^{H}H_{1}\overset{\_}{W}} \right)S_{1}} + {\left( {{\overset{\_}{W}}^{T}H_{2}^{T}H_{2}^{*}{\overset{\_}{W}}^{*}} \right)S_{1}} + {W^{H}H_{1}^{H}n_{1}} + {{\overset{\_}{W}}^{T}H_{2}^{T}n_{2}^{*}}}} & {{Equation}\mspace{14mu} 9}\end{matrix}$

Since W ^(T)H₂ ^(T)H*₂ W* is a real number, the the following Equation10 properties hold:W ^(T)H₂ ^(T)H*₂ W*=( W ^(T)H₂ ^(T)H*₂ W*)*= W ^(H)H₂ ^(H)H₂ W  Equation10

Equation 10 then implies the following Equation 11:W ^(H)H₁ ^(H)r₁+

^(T)H₂ ^(T)r*₂=( W ^(H)(H₁ ^(H)H₁+H₂ ^(H)H₂) W)S₁+

^(H)H₁ ^(H)n₁+

^(T)H₂ ^(T)n*₂   Equation 11

Similarly, therefore:−

^(T)H₂ ^(T)r*₁+

^(H)H₁ ^(H)r₂=( W ^(H)(H₁ ^(H)H₁+H₂ ^(H)H₂) W)S₂−

^(T)H₂ ^(T)n*₁+

^(H)H₁ ^(H)n_(s)   Equation 12

The signal to noise ratio for symbol S₁ is now given by Equation 13:

$\begin{matrix}\begin{matrix}{{{SNR}\left( S_{1} \right)} = \frac{\left( {{{\overset{\_}{W}}^{H}\left( {{H_{1}^{H}H_{1}} + {H_{2}^{H}H_{2}}} \right)}\overset{\_}{W}} \right)^{2}}{E\left\lbrack {\left( {{{\overset{\_}{W}}^{H}H_{1}^{H}n_{1}} + {{\overset{\_}{W}}^{T}H_{2}^{T}n_{2}^{*}}} \right)\left( {{{\overset{\_}{W}}^{H}H_{1}^{H}n_{1}} + {{\overset{\_}{W}}^{T}H_{2}^{T}n_{2}^{*}}} \right)^{*}} \right\rbrack}} \\{= \frac{\left( {{{\overset{\_}{W}}^{H}\left( {{H_{1}^{H}H_{1}} + {H_{2}^{H}H_{2}}} \right)}\overset{\_}{W}} \right)}{\sigma^{2}}}\end{matrix} & {{Equation}\mspace{14mu} 13}\end{matrix}$where σ²=E[n₁ ^(H)n₁]=E[n₂ ^(H)n₂] is the variance of the noise.

Similarly the SNR for symbol S₂ is given by Equation 14:

$\begin{matrix}{{{SNR}\left( S_{2} \right)} = \frac{\left( {{{\overset{\_}{W}}^{H}\left( {{H_{1}^{H}H_{1}} + {H_{2}^{H}H_{2}}} \right)}\overset{\_}{W}} \right)}{\sigma^{2}}} & {{Equation}\mspace{14mu} 14}\end{matrix}$

Maximization of Equations 13 and 14 with respect to the weight vectorimplies the calculation of the eigen vectors for the matrix (H₁^(H)H₁+H₂ ^(H)H²). Let V₁, V₂ indicate the two eigen vectors and μ₁, μ₂be the two corresponding eigen values. User station UST picks the eigenvector with the maximum eigen value implying that:μ₁>μ₂

=V₁μ₂>μ₁

=V₂   Equation 15

User station UST then sends back the weight values W₁ and W₂ back tobase station BST. Normalizing the weight W₁=1, user station UST canoptionally send back only the ratio (W₂/W₁) to base station BST and basestation BST then sets the weights on the antennas accordingly.

To further illustrate Equations 1 through 15 for simplicity, assume thatthere is only one multipath from base station BST to user station USTimplying that N=1. Given this assumption, then user station UST receivesthe following two symbols shown in Equations 16 and 17 afterdespreading:

$\begin{matrix}{r^{1} = {{W_{1}\left( {{\alpha_{1}^{1}S_{1}} - {\alpha_{2}^{1}S_{2}^{*}}} \right)} + {W_{2}\left( {{\alpha_{3}^{1}S_{1}} - {\alpha_{4}^{1}S_{2}^{*}}} \right)} + N_{2}}} & {{Equaion}\mspace{14mu} 16}\end{matrix}$

$\begin{matrix}{r^{2} = {{W_{1}\left( {{\alpha_{1}^{1}S_{2}} + {\alpha_{2}^{1}S_{1}^{*}}} \right)} + {W_{2}\left( {{\alpha_{3}^{1}S_{2}} + {\alpha_{4}^{1}S_{1}^{*}}} \right)} + N_{1}}} & {{Equaion}\mspace{14mu} 17}\end{matrix}$where N₁ and N₂ are additive white Guassian noise.

Rearranging Equations 16 and 17 yields the following Equations 18 and19, respectively:

$\begin{matrix}{r^{1} = {{S_{1}\left( {{W_{1}\alpha_{1}^{1}} + {W_{2}\alpha_{3}^{1}}} \right)} - {S_{2}^{*}\left( {{W_{1}\alpha_{2}^{1}} + {W_{2}\alpha_{4}^{1}}} \right)} + N_{2}}} & {{Equaion}\mspace{14mu} 18} \\{r^{2} = {{S_{2}\left( {{W_{1}\alpha_{1}^{1}} + {W_{2}\alpha_{3}^{1}}} \right)} + {S_{1}^{*}\left( {{W_{1}\alpha_{2}^{1}} + {W_{2}\alpha_{4}^{1}}} \right)} + N_{1}}} & {{Equaion}\mspace{14mu} 19}\end{matrix}$

For subsituting into Equations 18 and 19, and letting

${\overset{\sim}{\alpha} = \left( {{W_{1}\alpha_{1}^{1}} + {W_{2}\alpha_{3}^{1}}} \right)},{\overset{\sim}{\beta} = \left( {{W_{1}\alpha_{2}^{1}} + {W_{2}\alpha_{4}^{1}}} \right)},$then one skilled in the art will appreciate that Equations 18 and 19 arein the form of standard STTD implying that the total SNR for each symbolS₁ and S₂ after STTD decoding will be as shown in the following Equation20:

$\begin{matrix}\frac{{\left( {{W_{1}\alpha_{1}^{1}} + {W_{2}\alpha_{3}^{1}}} \right)}^{2} + {\left( {{W_{1}\alpha_{2}^{1}} + {W_{2}\alpha_{4}^{1}}} \right)}^{2}}{\sigma^{2}} & {{Equation}\mspace{14mu} 20}\end{matrix}$

Having detailed system 40, various of its advantages now may beobserved. For example, system 40 achieves a 2N path diversity where N isthe number of paths from base station BST to user station UST. Asanother example, versus an open loop approach alone, there is anincrease of a 3 dB gain in average SNR due to the use of closed looptransmit diversity across the two antenna groups (i.e., AT1 and AT2versus AT3 and AT4). As still another example, the required reverse linkbandwidth for providing the W₁ and W₂ feedback information is thatcorresponding to only two antennas while system 40 is supporting fourtransmit antennas. As a final example, the processing operations forreceiving data by user station UST may be implemented using standardSTTD decoding for each of the symbols S₁, S₂. From each of the precedingadvantages, one skilled in the art should appreciate that the preferredembodiment achieves better performance with a lesser amount ofcomplexity than is required in a prior art approach that increases thenumber of transmit antennas for a given (i.e., either closed or open)diversity scheme. As yet another advantage of the preferred embodiments,while such embodiments have been described in detail, varioussubstitutions, modifications or alterations could be made to thedescriptions set forth above without departing from the inventive scope.To further appreciate this inventive flexibility, various examples ofadditional changes contemplated within the preferred embodiments areexplored below.

While the example of system 40 has demonstrated the use of four transmitantennas, the inventive implementation of system 40 also may be appliedto wireless systems with other numbers of antennas, again using acombination of open loop transmit diversity and closed loop transmitdiversity as between subsets of the entire number of transmit antennas.For example, one alternative embodiment contemplated includes sixtransmit antennas, which for the sake of discussion let such antennas bereferred to as AT10 through AT15. With this system, open loop transmitdiversity may applied to pairs of those antennas, as with a firstantenna pair AT10 and AT11, a second antenna pair AT12 and AT13, and athird antenna pair AT14 and AT15. Further, closed loop transmitdiversity may then be applied between each of those pairs of antennas,whereby a first weight is applied to signals transmitted by the firstantenna pair, a second weight is applied to signals transmitted by thesecond antenna pair, and a third weight is applied to signalstransmitted by the third antenna pair. As another example, a combinationof open loop transmit diversity and closed loop transmit diversity maybe applied to a transmitter with eight antennas. In this case, however,various additional alternatives exist. For example, the eight antennasmay be split into four pairs of antennas, where open loop transmitdiversity is applied within each pair of antennas, and closed looptransmit diversity is applied as between each antenna pair (i.e., fourdifferent weights, one for each antenna pair). Alternatively, the eightantennas may be split into two sets of four antennas each, where openloop transmit diversity is applied within each set of four antennas, andclosed loop transmit diversity is applied as between the sets (i.e., twodifferent weights, one for each set of four antennas).

Also while the previous examples have demonstrated more than twotransmit antennas, it is recognized in connection with the presentinventive aspects that a combination of open loop transmit diversity andclosed loop transmit diversity may prove worthwhile for a transmitterwith only two transmit antennas. Specifically, instances may arise wherea transmitter in a closed loop diversity system receives feedback from areceiver to develop weights for future transmissions, but due to somefactor (e.g., high Doppler) the transmitter is informed of some reducedamount of confidence in the weights; for such an application, therefore,an alternative of the preferred embodiment may be created by adding anopen loop diversity technique to the closed-loop transmissions, therebycreating a combined diversity system. FIG. 5 illustrates an example ofsuch an application, and is now explored in greater detail.

FIG. 5 illustrates an open and closed loop encoder 60, and which may beincluded within a transmitter such as transmitter 42 described above inconnection with FIG. 4. Encoder 60 has an input 62, which by way ofexample is shown to receive a first symbol S₁ at a time T followed by asecond symbol S₂ at a time 2T, and again assume by way of example thatsymbols S₁ and S₂ are QPSK symbols. STTD encoder 32 has two outputs 64 ₁and 64 ₂, each connected to a respective antenna A60 ₁ and A60 ₂.

The operation of encoder 60 may be understood in view of the principlesdiscussed above, and further in view of the signals shown as output toantennas A60 ₁ and A60 ₂. For example, at time T′, antenna A60 ₁ outputsa combined signal formed by two addends, W₃W₁S₁+W₄S₁, while at the sametime T′ antenna A60 ₂ outputs a combined signal formed by two addends,W₃W₂S₁−W₄S₂*. The notion of combining an open and closed loop diversitymay be appreciated from these combined signals by looking at the addendsin each signal; specifically, as shown below, encoder 60 operates sothat for each signal transmitted it includes two addends, where thesecond-listed addend has a closed loop diversity and the first-listedaddend has an open loop diversity. Each of the diversity types isseparately discussed below.

To appreciate the open loop addends communicated by encoder 60, assumethat W₃=0 in which case the signals communicated by antennas A60 ₁ andA60 ₂ at time T′ reduce to the second-listed addends of the combinedsignals shown above. Specifically, for W₃=0, the signals output at timeT′ by encoder 60 reduce to an output of W₄S₁ by antenna A60 ₁ and anoutput of −W₄S₂* by antenna A60 ₂. By removing the common factor of W₄from these two addends, one skilled in the art will appreciate that theremaining factors (i.e., S₁ for antenna A60 ₁ and −S₂* for antenna A60₂) have an open loop diversity with respect to one another. This sameobservation with respect to open loop diversity may be found at time2T′. Specifically, if W₃=0, then the signals output at time 2T′ byencoder 60 reduce to an output of W₄S₂ by antenna A60 ₁ and an output ofW₄S₁* by antenna A60 ₂. By removing the common factor of W₄ from thesetwo addends, one skilled in the art will appreciate that the remainingfactors (i.e., S₂ for antenna A60 ₁ and S₁* for antenna A60 ₂) have anopen loop diversity with respect to one another.

To appreciate the closed loop addends communicated by encoder 60, assumethat W₄=0 in which case the signals communicated by antennas A60 ₁ andA60 ₂ at time T′ reduce to the first-listed addends of the combinedsignals shown above. Thus, for W₄=0, the signals output at time T′ byencoder 60 reduce to an output of W₃W₁S₁ by antenna A60 ₁ and an outputof W₃W₂S₁ by antenna A60 ₂. By removing the common factor of W₃ fromthese two addends, one skilled in the art will appreciate that theremaining factors (i.e., W₁S₁ for antenna A60 ₁ and W₂S₁ for antenna A60₂) have a closed loop diversity with respect to one another inasmuch asthey represent a product involving the same symbol but with a differentweight multiplied times each symbol. This same observation with respectto closed loop diversity may be found at time 2T. Specifically, if W₄=0,then the signals output at time 2T′ by encoder 60 reduce to W₃W₁S₂ byantenna A60 ₁ and an output of W₃W₂S₂ by antenna A60 ₂. Once more, byremoving the common factor of W₃ from these two addends, one skilled inthe art will appreciate that the remaining factors (i.e., W₁S₂ forantenna A60 ₁ and W₂S₂ for antenna A60 ₂) have an open loop diversitywith respect to one another.

Concluding the discussion of FIG. 5, it may be observed that encoder 60again supports a transmitter with two sets of transmit antennas, wherein this case each set consists of a single antenna rather than multipleantennas as in the previously-described embodiments. Nonetheless, thetransmitter receives feedback from its receiver in order to implementclosed loop diversity by applying different weights to some of thesymbols to form signals for communication by the transmitter (via itsencoder) while other of the signals communicated by the transmitterresult from symbols selectively modified according to an open loopdiversity technique.

As still another example of the present inventive scope, the types ofopen loop and closed loop transmit diversity also may be changed asapplied to the preferred embodiments. Thus, while TxAA has been shownabove as a closed loop technique, and STTD has been shown as an openloop technique, one or both of these may be replaced by correspondingalternative techniques and applied to a multiple transmit antennasystem, thereby again providing a combined closed loop and open looptransmit antenna system. Indeed, recall above an example is set forthfor an inventive system having eight antennas split into sets of fourantennas, where open loop transit diversity is applied within each setof four antennas. In this case, the application of open loop transmitdiversity as applied within a set of four antennas will require a typeof open loop diversity other than solely the transmission of conjugates;in other words, a use only of conjugates provides two different signals,whereas for four different antennas a corresponding four differentsignals are required to achieved the open loop diversity. Accordingly,for this as well as other embodiments, a different open loop diversityapproach may be implemented. For example, another open loop diversitytechnique that may be implemented according to the preferred embodimentincludes orthogonal transmit diversity (“OTD”), and which is shown for asingle OTD encoder 70 in FIG. 6 and for BPSK symbols. In FIG. 6, OTDencoder 70 is coupled to transmit symbols to four antennas A70 ₁ throughA70 ₄. Further, in operation, OTD encoder 70 buffers a number of symbolsequal to its number of antennas (i.e., four in the example of FIG. 6),and then each antenna transmits only one corresponding symbol and thatis in a form that is orthogonal to all other symbols transmitted alongthe other antennas. These forms are shown by way of the output symbolsin FIG. 6 along antas A70 ₁ through A70 ₄ from time T′ through time 4T.Further, for simplicity FIG. 6 only illustrates the OTD operation and,thus, does not further show the use of weighting to achieve the combinedclosed loop diversity. Nonetheless, the addition of a closed loopweighting operation should be readily implemented by one skilled in theart given the preceding teachings with respect to other embodiments. Asanother example of an alternative open loop diversity that may be usedaccording to the preferred embodiments, FIG. 7 illustrates an STTDencoder 80 for four antennas A80 ₁ through A80 ₄. The conventions ofFIG. 7 should be readily appreciated from the preceding examples, wherethe signals transmitted along antennas A80 ₁ through A80 ₄ thereforerepresent open loop diverse signals, and for the example where thesymbols are BPSK symbols. Also as in the case of FIG. 6, for simplicityFIG. 7 only illustrates the open loop diversity operation (i.e., STTD)and, thus, FIG. 7 does not furhter show the use of weighting to achievethe combined closed loop diversity, where such additional weighting maybe implemented by one skilled in the art according to the teachings ofthis document. As still another example of an alternative open loopdiversity that may be used according to the preferred embodiments, FIG.8 illustrates time switched time diversity (“TSTD”) for four antennas.Lastly, other closed loop diversity techniques that may be used tocreate still further alternative embodiments include switched diversity.

As still another example of the inventive scope, note that various ofsuch teachings may be applied to other wireless systems. For example,the preceding may be applied to systems complying with the 3^(rd)Generation partnership Project (“3GPPP”) for wireless communications,and to 3GPPP 2 systems, as well as still other standardized ornon-standardized systems. Further, while the preceding example has beenshown in a CDMA system (or a WCDMA system), the preferred embodiment maybe implemented by including transmitter antenna diversity combining bothopen loop and closed loop diversity in a time division multiple access(“TDMA”) system, which has a spreading gain of one.

As a final example of the inventive scope, while the precedingembodiments have been shown in connection with a receiver having only asingle antenna, note that systems using multiple receive antennas alsoare contemplated. In other words, therefore, the preceding also may becombined with various techniques of receive antenna diversity.

From the preceding, one skilled in the art should appreciate variousaspects of the inventive scope, as is defined by the following claims.

1. A wireless communication system, comprising: transmitter circuitrycomprising encoder circuitry for receiving a plurality of symbols; aplurality of antennas coupled to the transmitter circuitry and fortransmitting signals from the transmitter circuitry to a receiver,wherein the signals are responsive to the plurality of symbols; andwherein the encoder circuitry is for applying space time block codedtransmit antenna open loop diversity and closed loop diversity to theplurality of symbols to form the signals; wherein the plurality ofantennas comprises a pluraltty plurality of sets of antennas; whereinfor each of the sets of antennas the encoder circuitry is for applyingspace tile time block coded transmit antenna diversity to selected onesof the plurality of symbols such that signals transmitted by any oneantenna in the set of antennas represent open loop diversity withrespect to signals transmitted by any other antenna in the set ofantennas; and wherein for each of the sets of antennas the encodercircuitry is for applying a weight to the plurality of symbols such thatsignals fitted in response to the weight represent a closed loopdiversity with respect to signals transmitted by any other antenna inany other of the sets of antennas.
 2. The system of claim 1: wherein theplurality of sets of antennas consists of two sets of antennas; andwherein each of the sets of antennas consists of two antennas.
 3. Thesystem of claim 1: wherein the plurality of sets of antennas consists ofthree sets of antennas; and wherein each of the sets of antennasconsists of two antennas.
 4. The system of claim 1: wherein theplurality of sets of antennas consists of two sets of antenas; andwherein each of the sets of antennas consists of four antennas.
 5. Thesystem of claim 1: wherein the plurality of sets of antennas consists offour sets of antennas; and wherein each of the sets of antennas consistsof two antennas.
 6. The system of claim 1 wherein the closed loopdiversity comprises transmit adaptive array diversity.
 7. The system ofclaim 1 and further comprising the receiver.
 8. The system of claim 7wherein the receiver comprises one antenna for receiving the signalstransmitted from the plurality of antennas.
 9. The system of claim 7wherein the receiver comprises a plurality of antennas, wherein each ofthe plurality of antennas is for receiving the signals transmitted fromthe plurality of antennas.
 10. The system of claim 7 wherein thereceiver comprises decoder circuitry for decoding open loop diversityand closed loop diversity with respect to the plurality of symbols. 11.The system of claim 10 wherein the receiver further comprises: adespreader having an output and for producing a despread symbol streamat the output in response to the signals, wherein the output is coupledto the decoder circuitry; a channel estimator coupled to the output ofthe despreader and for determining estimated channel impulse responsesbased on the despread symbol stream; and wherein the decoder circuitryis for decoding open loop diversity and closed loop diversity withrespect to the despread symbol stream and in response to the estimatedchannel impulse responses.
 12. The system of claim 11 wherein thereceiver further comprises a deinterleaver coupled to an output of thedecoder circuitry and for providing an inverse interleaving functionwith respect to information received from the decoder circuitry.
 13. Thesystem of claim 12 wherein the receiver further comprises a channeldecoder coupled to an output of the deinterleaver and for improving adata error rate of information received from the deinterleaver.
 14. Thesystem of claim 1 wherein the signals comprise CDMA communications. 15.The system of claim 1 wherein the signals comprise WCDMA communications.16. The system of claim 1 wherein the signals comprise TDMAcommunications.
 17. The system of claim 1: wherein the transmittercircuitry is located in a base station; and wherein the receivercomprises a mobile receiver.
 18. The system of claim 1 wherein theplurality of symbols comprise quadrature phase shift keying symbols. 19.The system of claim 1 wherein the plurality of symbols comprise binaryphase keying symbols.
 20. The system of claim 1 wherein the plurality ofsymbols comprise quadrature amplitude modulation symbols.
 21. The systemof claim 1 wherein the transmitter circuitry further comprises: achannel encoder for receiving a plurality of bits; an interleavercoupled to an output of the channel encoder and for shuffling a block ofencoded bits; and a symbol mapper coupled to an output of theinterleaver for converting shuffled bits into the plurity of symbols.22. A wireless communication receiver for receiving signal fromtransmitter circuitry transmitting along a plurality of sets of transmitantennas, wherein the signals are formed by the transmitter circuitry byapplying space time block coded transmit antenna diversity to selectedones of the plurality of symbols such that signals transmitted by anyone antenna in the set of antenas represent space time block coded openloop diversity with respect to signals transmitted by any other antennain the set of antennas and wherein for each of the sets of antennas theencoder circuitry is for applying a weight to the plurality of symbolssuch that signals transmitted in response to the weight represent aclosed loop diversity with respect to signals transmitted by any otherantenna in any other of the uses of antennas, the receiver comprising adespreader having an output and for producing a despread symbol streamat the output in response to the signals; and decoder circuitry coupledto the output of the despreader and for decoding space time block codedopen loop diversity and closed loop diversity with respect to thedespread symbol stream.
 23. The receiver of claim 22 and furthercomprising one antenna for receiving the signals transmitted from theplurality of transmit antennas.
 24. The receiver of claim 22 and furthercomprising a plurality of antennas for receiving the signals transmittedfrom the plurality of transmit antennas.
 25. The receiver of claim 22and further comprising: a channel estimator coupled to the output of thedespreader and for determining estimated channel impulse responses basedon the despread symbol stream; and wherein the decoder circuitry is fordecoding space time block coded open loop diversity and closed loopdiversity with respect to the despread symbol strum and in response tothe estimated channel impulse responses.
 26. The receiver of claim 25and further comprising a deinterleaver coupled to an output of thedecoder circuitry and for providing an inverse interleaving functionwith respect to information received from the decoder circuitry.
 27. Thesystem of claim 26 and further comprising a channel decoder coupled toan output of the deinterleaver and for improving a data error rate ofinformation received from the deinterleaver.
 28. A method of operating awireless communication system, comprising the steps of receiving aplurality of symbols into encoder circuitry; applying space time blockcoded open loop diversity and closed loop diversity to the plurality ofsymbols to form a plurality of signals; and transmitting the pluralityof signals along a plurality of antenna to a receiver; wherein theplurality of antennas comprises a plurality of sets of antennas; andwherein the step of applying space time block coded open loop diversityand closed loop diversity applies space time block coded open loopdiversity to selected ones of the plurality of symbols such that signalstransmitted by any one antenna in the set of antennas represent openloop diversity with respect to signals transmitted by any other antennain the set of antennas.
 29. The method of claim 28 wherein for each ofthe sets of antennas the step of applying open loop diversity and closedloop diversity applies a weight to the plurality of symbols such thatsignals transmitted in response to the weight represent a closed loopdiversity with respect to signals transmitted by any other antenna inany other of the sets of antennas.
 30. A diversity encoder circuit for awireless communication system, comprising: an input terminal coupled toreceive a first symbol and a second symbol, each symbol having pluraldata bits; a first output terminal coupled to a first antenna andarranged to produce a product of a first scalar weight and one of thefirst symbol and a conjugate of the first symbol at a first time and aproduct of a second scalar weight and one of the second symbol andnegative conjugate of the second symbol at a second time; and a secondoutput terminal coupled to a second antenna and arranged to produce aproduct of a third scalar weight and one of the second symbol andnegative conjugate of the second symbol at the first time and a productof a fourth scalar weight and one of the first symbol and the conjugateof the first symbol at the second time.
 31. A diversity encoder circuitas in claim 30, comprising: a third output terminal coupled to a thirdantenna and arranged to produce a product of the third scalar weight andthe first symbol at a first time and a product of the fourth scalarweight and the second symbol at a second time; and a fourth outputterminal coupled to a fourth antenna and arranged to produce a productof the first scalar weight and the negative conjugate of the secondsymbol at the first time and a product of the second scalar weight andthe conjugate of the first symbol at the second time.
 32. A diversityencoder circuit as in claim 31, wherein the first scalar weight is equalto the second scalar weight, and wherein the third scalar weight isequal to the fourth scalar weight.
 33. A diversity encoder circuit as inclaim 30, wherein the symbols comprise one of CDMA symbols, WCDMAsymbols, and TDMA symbols.
 34. A diversity encoder circuit as in claim30, comprising a transmitter circuit located at a base station.
 35. Adiversity encoder circuit as in claim 30, wherein the first and secondsymbols comprise quadrature phase shift keying symbols.
 36. A diversityencoder circuit as in claim 30, wherein the first and second symbolscomprise quadrature amplitude modulation symbols.
 37. A diversityencoder circuit as in claim 30, wherein the first and second symbolscomprise binary phase shift keying symbols.
 38. A diversity encodercircuit as in claim 30, wherein the first scalar weight is equal to thesecond scalar weight, and wherein the third scalar weight is equal tothe fourth scalar weight.
 39. A diversity decoder circuit for a wirelesscommunication system, comprising: an input terminal coupled to receive aproduct of a first scalar weight and one of a first symbol and aconjugate of the first symbol from a first antenna of a remotetransmitter and a product of a third scalar weight and one of a secondsymbol and negative conjugate of the second symbol at a first time froma second antenna of the remote transmitter, wherein the input terminalis coupled to receive a product of a second scalar weight and one of thesecond symbol and negative conjugate of the second symbol and a productof a fourth scalar weight and one of the first symbol and the conjugateof the first symbol at a second time from the remote transmitter; and adecoder coupled to the input terminal and producing the first symbol andthe second symbol.
 40. A diversity decoder circuit as in claim 39,wherein the first scalar weight is equal to the second scalar weight,and wherein the third scalar weight is equal to the fourth scalarweight.
 41. A diversity decoder circuit as in claim 39, wherein theinput terminal is coupled to receive the product of the first scalarweight and the first symbol and the product of the third scalar weightand the negative conjugate of the second symbol at the first time andthe product of the second scalar weight and the second symbol and theproduct of the fourth scalar weight and the conjugate of the firstsymbol at the second time.
 42. A diversity decoder circuit as in claim41, wherein the input terminal is coupled to receive the product of thefirst scalar weight and the first symbol from the first antenna, theproduct of the third scalar weight and the negative conjugate of thesecond symbol from the second antenna, a product of the first scalarweight and the negative conjugate of the second symbol from a thirdantenna, and a product of the third scalar weight and the first symbolfrom a fourth antenna, and wherein the first, second, third, and fourthantennas are coupled to a remote transmitter.
 43. A diversity decodercircuit as in claim 39, wherein the symbols comprise one of CDMAsymbols, WCDMA symbols, and TDMA symbols.
 44. A diversity decodercircuit as in claim 39, wherein the wireless communication systemcomprises a wireless user station.
 45. A diversity decoder circuit as inclaim 39, wherein the first and second symbols comprise quadrature phaseshift keying symbols.
 46. A diversity decoder circuit as in claim 39,wherein the first and second symbols comprise quadrature amplitudemodulation symbols.
 47. A diversity decoder circuit as in claim 39,wherein the first and second symbols comprise binary phase shift keyingsymbols.
 48. A method of diversity encoding a signal for transmission toa remote wireless communication circuit, comprising the steps of:producing a first product of a first weight and a first symbol at afirst time; producing a second product of a second weight and a secondsymbol at a second time; producing a third product of a third weight anda negative conjugate of the second symbol at the first time; producing afourth product of a fourth weight and a conjugate of the first symbol atthe second time; applying the first and second products to a firstantenna; and applying the third and fourth products to a second antenna,wherein each of the first and second weights is determined in responseto a channel effect between the first antenna and the remote wirelesscommunication circuit, and wherein each of the third and fourth weightsis determined in response to a channel effect between the second antennaand the remote wireless communication circuit.
 49. A method as in claim48, wherein the first weight is equal to the second weight, and whereinthe third weight is equal to the fourth weight.
 50. A method as in claim48, comprising the steps of: applying a product of the first weight anda negative conjugate of the second symbol to a third antenna at thefirst time; applying a product of the second weight and the conjugate ofthe first symbol to the third antenna at the second time; applying aproduct of the third weight and the first symbol to a fourth antenna atthe first time; and applying a product of the fourth weight and thesecond symbol to the fourth antenna at the second time.
 51. A method asin claim 48, wherein the symbols comprise one of CDMA symbols, WCDMAsymbols, and TDMA symbols.
 52. A method as in claim 48, wherein thefirst and second symbols comprise quadrature phase shift keying symbols.53. A method as in claim 48, wherein the first and second symbolscomprise quadrature amplitude modulation symbols.
 54. A method as inclaim 48, wherein the first and second symbols comprise binary phaseshift keying symbols.
 55. A method as in claim 50, wherein the firstweight is equal to the second weight, and wherein the third weight isequal to the fourth weight.
 56. A method of diversity decoding a signalfrom a remote wireless communication circuit, comprising the steps of:receiving a first product of a first weight and a first symbol at afirst time from a first antenna of the wireless communication circuit;receiving a third product of a third weight and a negative conjugate ofa second symbol at the first time from a second antenna of the wirelesscommunication circuit, wherein the first weight is determined inresponse to a channel effect from the first antenna of the remotewireless communication circuit, and wherein the third weight isdetermined in response to a channel effect from the second antenna ofthe remote wireless communication circuit; decoding the first and thirdproducts; and producing the first symbol and the second symbol.
 57. Amethod as in claim 56, comprising the steps of: receiving a secondproduct of a second weight and the second symbol at a second time fromthe first antenna of the wireless communication circuit; and receiving afourth product of a fourth weight and a conjugate of the first symbol atthe second time from the second antenna of the wireless communicationcircuit, wherein the second weight is determined in response to achannel effect from the first antenna of the remote wirelesscommunication circuit, and wherein the fourth weight is determined inresponse to a channel effect from the second antenna of the remotewireless communication circuit.
 58. A method as in claim 57, comprisingthe steps of: receiving a product of the first weight and the negativeconjugate of the second symbol from a third antenna at the first time;receiving a product of the third weight and the first second symbol froma fourth antenna at the first time; receiving a product of the secondweight and the conjugate of the first symbol from the third antenna atthe second time; and receiving a product of the fourth weight and thesecond symbol from the fourth antenna at the second time.
 59. A methodas in claim 58, wherein the first weight is equal to the second weight,and wherein the third weight is equal to the fourth weight.
 60. A methodas in claim 56, comprising a wireless user station.
 61. A method as inclaim 56, wherein the first and second symbols comprise quadrature phaseshift keying symbols.
 62. A method as in claim 56, wherein the first andsecond symbols comprise quadrature amplitude modulation symbols.
 63. Amethod as in claim 56, wherein the first and second symbols comprisebinary phase shift keying symbols.
 64. A method as in claim 57, whereinthe first weight is equal to the second weight, and wherein the thirdweight is equal to the fourth weight.
 65. A method of diversity encodinga signal for transmission to a remote wireless communication circuit,comprising the steps of: receiving a plurality of data symbols includinga first symbol and a second symbol, each symbol having plural data bits;receiving a plurality of weights from the remote wireless communicationcircuit; producing a first product of a first weight and the firstsymbol at a first time; producing a second product of a second weightand a second symbol at a second time; producing a third product of athird weight and a negative conjugate of the second symbol at the firsttime; producing a fourth product of a fourth weight and a conjugate ofthe first symbol at the second time; applying the first and secondproducts to a first antenna; and applying the third and fourth productsto a second antenna.
 66. A method as in claim 65, wherein the first andfourth weights are different.
 67. A method as in claim 65, wherein thefirst weight is equal to the second weight, and wherein the third weightis equal to the fourth weight.
 68. A method as in claim 65, wherein thefirst symbol comprises one of a CDMA symbol, a WCDMA symbol, and a TDMAsymbol.
 69. A method as in claim 65, wherein the first symbol comprisesa quadrature phase shift keying symbol.
 70. A method as in claim 65,wherein the first symbol comprises a quadrature amplitude modulationsymbol.
 71. A method as in claim 65, wherein the first symbol comprisesa binary phase shift keying symbol.
 72. A method of diversity decoding asignal from a remote wireless communication circuit, comprising thesteps of: receiving a first product of a first weight and a first symbolat a first time from a first antenna of the remote wirelesscommunication circuit; receiving a second product of a second weight andthe second symbol at a second time from the first antenna of the remotewireless communication circuit; receiving a third product of a thirdweight and a negative conjugate of a second symbol at the first timefrom the second antenna of the remote wireless communication circuit;receiving a fourth product of a fourth weight and a conjugate of thefirst symbol at the second time from a second antenna of the remotewireless communication circuit; and decoding the first and fourthproducts and producing the first symbol.
 73. A method as in claim 72,wherein the first and fourth weights are different.
 74. A method as inclaim 72, wherein the first weight is equal to the second weight, andwherein the third weight is equal to the fourth weight.
 75. A method asin claim 72, comprising receiving the first and fourth products at awireless user station.
 76. A method as in claim 72, wherein the firstsymbol comprises a quadrature phase shift keying symbol.
 77. A method asin claim 72, wherein the first and second symbols comprise quadratureamplitude modulation symbols.
 78. A method as in claim 72, wherein thefirst and second symbols comprise binary phase shift keying symbols.